Problem running diskcopy in WindowsXP

Has anyone out there seen and found an answer to the (Microsoft’s KB# 811839) problem with WinXP Pro of trying to diskcopy a floppy disk (yes, we still use floppies – we’re a college and can’t yet get rid of them). We have found that it will not work if there are any open files (of course), or there are any unrecognized file formats on the disk. But it does not work in DOS, either! We can use these general rules of thumb, and then it still won’t copy the disk. Swapping disks helps some times, but we’re really looking for a solution where we can tell our students EXACTLY what steps to take to produce a duplicate disk. Thanks.